Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known as human herpes virus 1 and 2 (HHV-1 and -2), are enveloped double-stranded DNA viruses and belong to the herpes virus family, Herpesviridae. Generally, the HSV virus infects humans in the skin or mucous membranes of the mouth (HSV-1) and genitals (HSV-2). The HSV virus is capable of establishing life-long latent infections after the primary infections, and reactivating from latency for new outbreaks. HSV infections generally involve eruption of tiny blisters on the skin or mucous membranes, after which the virus remains in a dormant state inside nerve cells supplying the infected area. The virus undergoes cycles of re-activation in which the virus travels through the nerve fibers back to the skin and thereby causes eruptions of blisters in the same area of skin as the earlier infection. There are also cases not involving the formation of blisters.
HSV is the causative agent of a variety of disorders, including blindness and encephalitis. If left untreated, the mortality rate for the latter disease is as high as 70%, as opposed to only 19% among those who receive treatment. About 38% of the treated patients recover completely, which underscores the importance of diagnosing HSV infection at an early stage. HSV-1 mostly causes adult encephalitis, whereas HSV-2 more commonly causes newborn encephalitis, the latter being associated with maternal genital infections. Furthermore, HSV-2 is one of the most common sexually transmitted diseases in society. The fatality rate of HSV-related encephalitis is higher than that of all other types of encephalitis, being 1 to 4 per million per year. The large variety of its symptoms may include fever, headaches, seizures, an altered level of consciousness, and personality changes.
Traditionally, it is believed that HSV-1 causes oral infection, while HSV-2 causes genital infection. However, HSV-1 is a more frequent cause of primary genital herpes and often co-infects with HSV-2 in many developed countries. As a result, it becomes very important to have a PCR assay that is capable to detect and discriminate both viruses simultaneously. This new HSV assay is designed to accomplish that in a single reaction tube.
Diagnosis of HSV-1 and/or HSV-2 (HSV-1/2) infections is commonly performed using cell culture on appropriate clinical specimens, which is time consuming and labor intensive. In addition, serologic diagnosis of HSV-1/2 infections lacks sufficient sensitivity and specificity. Thus there is a need in the art for a quick and reliable method to specifically detect both types of HSV in a sensitive manner.